Some catalysts may be known as honeycomb or pouring layer catalysts. Aqueous solutions from a first component of a compound with lanthanum, cerium and cobalt, a second component platinum, a third component rhodium, and a fourth component from a wash coat of alumina, titanium dioxide and oxalic acid may be applied to the catalyst. One disadvantage of these honeycomb or pouring layer catalysts may be the small surface of the active substance, which is supplemented to a sufficient catalytic effect by the additional use of platinum and rhodium. Thus, the compounds of lanthanum, cerium and cobalt only act as an improved surface for the platinum, and allow an increased lifetime.
Surprisingly, it has now been found that when the level of platinum is almost completely substituted, the lifetime is increased, and the catalytic effect is substantially improved if the active substance is crystallized from rare earths and cobalt in multiple stages. Furthermore, the substances cobalt and manganese, and the rare earths lanthanum, cerium and yttrium may be used to transform the crystals, with a diameter from 1 to 0.1 μm and a length from 100 to 100,000 μm in a special multi-stage process.